Different Types of Coral: A Guide to Understanding Them

Have you ever wondered what different types of corals exist and how they are classified? As a passionate diver, you know that exploring the underwater world reveals hidden wonders in every dive. Among these wonders, corals stand out as living jewels, forming impressive structures that host incredible biodiversity. But do you know how many different types of corals there are? And how many types of reefs?

In this article, we will explore in detail the different types of corals, their classification, and what makes each one unique. Get ready to discover everything you didn’t know about these flowering animals!

1. What Are the Main Different Types of Corals?

Corals belong to the phylum Cnidaria, which also includes jellyfish and sea anemones. Within this phylum, most types of corals are classified in the class Anthozoa, although some are placed in the class Hydrozoa.

An etymological curiosity:

The name “Anthozoa” derives from the Greek words άνθος (ánthos; “flower”), referring to their polyps, and ζώα (zóa; “animals”), because they are animals, even though many people still think they are plants. This results in ανθόζωα (anthozoa), meaning “flower animals.”

Let’s get to know these flower animals in more depth!

In the quest to distinguish between different types of corals, we can start with a basic classification into:

(Hermatypic) or hard corals: these corals are capable of building reefs due to their hard skeleton made of calcium carbonate.

(Ahermatypic) or soft corals: these do not build reefs and have a softer tissue.

But this is a quite simple classification, suitable for primary schools. As coral enthusiasts, we want to go deeper.

2. How Many Different Corals Are There in Fact?

There are mainly four types of corals. The three most common types of corals belong to the class Anthozoa, the flower corals—remember?—and the rarer ones, the Hydrozoa.

The class Anthozoa is further divided into three subclasses: Hexacorallia, Octocorallia, and Ceriantharia.

Hexacorallia

This type of coral is distinguished by having individual polyps, which are sack-shaped animals open to the outside with a mouth surrounded by tentacles.

The tentacles of this class of corals exhibit radial symmetry in six parts (meaning the tentacles are multiples of six). This feature stands out among the different types of corals.

In various species, these polyps can live in colonies and have the ability to secrete a skeleton of calcite, called a coralite, which protects their soft and delicate bodies.

In the Caribbean waters, most species grow in colonies, joining their coralites to create large and strong structures. The colonies expand with new polyps and stack on top of each other over time.

Therefore, the most important type of corals in this subclass are the stony corals, the hard ones, the hermatypic ones—the type of corals that create reefs. These are of the order Scleractinia, but so are sea anemones and zoanthids.

Octocorallia

Octocorallia are one of the various types of corals found in the oceans and are distinguished from the rest by several key characteristics. They exhibit octagonal symmetry, meaning each polyp has eight tentacles and eight mesenteries. This symmetry is different from the hexagonal symmetry of stony corals (Hexacorallia).

Regarding their structure, many Octocorallia are considered soft corals. However, some, like the blue coral, can have calcium carbonate skeletal structures, but these are not as robust as those of stony corals.

Among the different types of coral in the subclass Octocorallia, gorgonians are the most prominent. These corals are known for their branching structures that can resemble fans or feathers, and you can learn almost everything about them by reading this article: Gorgonians: Inside the Caribbean Sea Fan Forest

There are also Telestaceans and other soft corals.

Ceriantharia

Ceriantharia are one of the different types of corals found in the deep ocean. They are also known as black corals due to their color and because they inhabit deep waters.

Although many species can be seen while diving in the Caribbean, some even grow in surprisingly shallow waters.

Black coral polyps do not form “homes” of corallite like stony corals; instead, they live directly on the skeletal surface of their branches. They secrete a proteinaceous material, generally black in color, which becomes extremely hard and resistant through a tanning process (similar to leather). This material is deposited in concentric layers, forming wire-like branches (skeleton). When a branch is cut cross-sectionally, these layers resemble the growth rings of a tree.

3. What Is the Rarest Type of Coral?

Corals of the Hydrozoa Class

Hydrocorals are colonies that secrete hard, calcareous skeletons. They are often thought to be hard corals, but they are not. There are two types: fire corals and lace corals.

Fire coral: Stinging coral as it is sometimes called, usually causes a painful burning sensation when touched with bare skin. This reaction is caused by the powerful batteries of stinging nematocysts in the tentacles of the small polyps.

Lace corals: The common name for this type of coral comes from their thin, delicate branches that form a hard calcareous skeleton in a lace-like pattern.

4. What Are the Different Types of Coral Reefs?

Have you ever wondered how many different types of coral reefs there are? Well, coral reefs are much more diverse than you might imagine, and although there are many shapes and sizes, scientists usually talk about three main types. However, some experts say there could be up to five. Let’s break down the different types of coral reefs in a simple way.

1. Fringing Reefs These are the youngest and most common. They grow along the coast or around islands and are separated from the land by a shallow lagoon. They generally follow the coastline and are considered shallow reefs, to the point that in some areas they nearly touch the surface. They can be found on many Caribbean islands and are prominent in the Bahamas, but interestingly, they are almost absent along the coasts of Florida and the Keys. These fringing reefs can transform into barrier reefs when the associated land slowly sinks.
2. Barrier Reefs This type of coral reef is a bit farther from the coast. Although they grow parallel to it, they are separated by a deeper and wider lagoon. The distance can vary from 1 mile (1.6 kilometers) to 25 miles (40 kilometers) or more, and the lagoon can be more than 60 feet (20 meters) deep. The shallowest part of the barrier reefs also comes close to the surface, forming a “barrier” that can hinder navigation. The best example in the world is the Great Barrier Reef.
3. Atolls These are the most impressive, forming rings or horseshoe shapes in open sea around a shallow lagoon. Atolls are generally found in the tropical Pacific and form when a volcanic island sinks, leaving only the lagoon surrounded by the reef. Although there are some in the Western Atlantic, they did not form from volcanoes like those in the Pacific. Well-known examples include Lighthouse and Glover’s in Belize, Chinchorro off the coast of Yucatán, and Hogsty in the Bahamas.
4. Bank Reefs These are less known and are found in open sea. Some classify them as atolls, but they are surrounded by deep water and many miles away from any land. Famous examples are the Great Bahama Bank and the 12-Mile Bank near Grand Cayman, also known as the 4th Cayman Island.
5. Patch Reefs Finally, we have patch reefs. These are small reef areas that grow isolated from the seafloor. They are usually found between fringing and barrier reefs. A patch reef can vary in size, from something as small as a house to an area that could cover several city blocks. Their depth also varies, but they rarely break the surface of the water.

So there you have it, a quick guide to the different types of coral reefs. Each one is unique and plays a vital role in marine ecosystems. Next time you go diving, you’ll know exactly what type of reef you’re exploring!

5. What Are the Different Types of Corals Based on Their Location on The Reef?

Let’s talk now about the different types of coral reefs in relation to the structures that make them up and their parts.

First, let’s discuss coral heads. These are like mini-reefs, but smaller. They are usually made up of a single coral colony, such as brain coral or giant star coral, although they can sometimes include several smaller colonies of the same species or different ones.

Next, we have the reef crest, which is the top part of a reef system. It’s like the roof of the reef, where the waves usually break.

The back reef is the area located behind the coastal reefs. It is a calm, protected zone that often features small coral heads, reef patches, and seagrass. It’s a perfect spot for more tranquil marine life.

The lagoon is another calm and protected area found behind a coastal or barrier reef. It is shallow and usually filled with extensive sand flats, seagrass beds, and occasionally some coral heads.

The reef front is the part of the reef facing the open sea, extending into deeper waters. It is where the ocean’s action becomes more intense.

Now let’s talk about the tongue and groove. These are long ridges separated by sand valleys that generally run in the direction of the prevailing waves. These grooves are typically found in shallow waters near the reef crest but can also be located on the reef front. The ridges are known as spur or buttresses, and the valleys are called sand channels or canyons if they are narrow and steep-sided.

Finally, we have the walls, which are loved by divers. These are like underwater cliffs that drop almost at a 90-degree angle. Walls are usually found on the outer edges of an island platform or continental shelf. Just at the top of these walls, sometimes wall lips form, which are like ridges running along the upper edge and can be up to 20 or 30 feet high.

These are just some of the terms and types of structures that make up coral reefs. Interesting, right? So next time you’re asked how many different types of coral reefs there are, you’ll have a clear idea of their features and what makes them unique.

6. How Many Different Species of Coral Are There?

If you’ve ever wondered how many different types of coral species exist, the answer will surprise you. Worldwide, it is estimated that there are around 6,000 species of marine corals. Yes, six thousand!

For example, approximately 60 species of reef-building corals have been identified in Mexico alone. This represents between 8% and 10% of all known species in the world. In the Caribbean, at least 50 different species of stony corals have been recorded, each with its own unique skeletal structure.

In Panama, specifically in the Bocas del Toro archipelago, 65 different species of corals have been found, including some species that have been recently discovered.

In summary, the diversity of corals is astonishing and plays a crucial role in marine life. If you were wondering how many different types of coral there are, now you know they are classified into stony corals, which build reefs, and various types of soft corals, which lack a hard skeleton but are equally fascinating.

In conclusion, as a diver, you can now enjoy this rich biodiversity. However, it is important to emphasize the need to protect our oceans and the different types of corals that inhabit them. Each species is unique and essential for the balance of marine ecosystems!

Are you coming to see them?